A so-called 3D user experience in medical applications essentially includes two components: a) time taken to load the images of a volume from a database or data store into the main memory of the application and b) time taken to produce a 3D image using a so-called volume rendering method.
It is possible with regard to the above point b) to use different algorithms, the algorithms assuming that all the images of a volume are already loaded into the main memory. This is an essential variable, which impacts significantly on the 3D user experience and has not yet been optimized.
Also the data volumes to be loaded into the main memory in the medical field are increasing all the time, as medical modalities increasingly produce larger studies and individual examinations using the modalities often generate not just one but a number of studies, as for example with multirow CT.
Against a background of workflows with very short cycles in medical facilities, it is favorable for the acceptance of medical software that the medical personnel do not have to tolerate waiting times. The software should be able to present multidimensional volumes, in particular 3D or 4D volumes, of any size to the user in such a manner that no waiting times are perceived either when loading the images into the main memory or during volume rendering.
There are methods for improving 3D user experience which perform optimization of volume rendering for images of the volume already loaded into the main memory. This means that the user cannot see a 3D image until all the images of the volume have been loaded into the main memory. Once all the images have been loaded into the main memory, different methods are available for shortening the time required for volume rendering. 3D volume rendering cannot take place until all the images of a medical series have been loaded into the main memory. The bigger the series, the longer the waiting times that have to be tolerated.
One possible method, known as texture-based volume rendering, is based on the volume being divided into distinct three-dimensional so-called bricks and the bricks being rendered one after the other. The quality of the rendered images before all the bricks are loaded in medical imaging in particular can allow diagnosis errors to occur, because one brick represents only one predetermined three-dimensional region of the entire volume. A number of loaded bricks therefore reveal a larger region of the volume, while other regions of the volume remain invisible to the viewer.
One improvement to texture-based volume rendering is the known method of progressive refinement for texture-based volume rendering, as disclosed in U.S. Pat. No. 7,843,452 B2. It is likewise assumed here that all the images of the volume have been loaded into the main memory. Texture-based volume rendering is then used in a modified form, so that the bricks are first loaded with a low resolution and then better and better resolutions of the bricks are continuously loaded until the highest resolution of each brick has been loaded.
The time taken for volume rendering for images already loaded into the main memory is thus optimized. As medical studies become ever larger, the time taken to load the images into the main memory should also be optimized and the volume rendering should be matched to this, in order to achieve a favorable user experience.